− v 2 u 4 + v u 4 + 5 v 2 u 3 − 8 v u 3 + 4 u 3 − 8 v 2 u 2 + 15 v u 2 − 8 u 2 + 4 v 2 u − 8 v u + 5 u + v − 1 {\displaystyle -v^{2}u^{4}+vu^{4}+5v^{2}u^{3}-8vu^{3}+4u^{3}-8v^{2}u^{2}+15vu^{2}-8u^{2}+4v^{2}u-8vu+5u+v-1}
